The present invention is directed to electronic packaging and, more particularly, is directed to a method to repair defective electrical connections in a multilayer ceramic package.
Multilayer Ceramic (“MLC”) substrates may contain thousands of electrical connections. There are numerous manufacturing problems which can result in a defective electrical circuit, or “net”, within an MLC substrate. The two most common defects are simple open circuits or shorted circuits. Once an MLC substrate has been fired, it is very difficult to repair an electrical defect since the defective electrical connection is contained within the substrate. The current method used to repair a defective electrical net is to build a new electrical connection on the top surface of the substrate using conventional thin films technology. This method often involves building a multilayer repair structure on the top surface of the MLC substrate. While the thin film repair technology is very effective, it is also costly due to the number of process steps and high resolution tooling required.
Therefore, there is a need for a low cost alternative to repair defective electrical connections or nets in MLC substrates. Accordingly, it is a purpose of the present invention to provide a novel process to repair defective nets within an MLC substrate. The method involves using numerically controlled tooling to define and form an electrical connection between a defective net within an MLC substrate to a repair net. This repair net is a redundant net placed within the MLC substrate. This new repair method does not rely on thin film structures; rather the repair is embedded into the surface of the MLC substrate through a laser ablation process and metal deposition process.